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Circuit SimulatorBeta

Inverting Op-Amp Amplifier

An inverting amplifier scales a signal by a factor set only by two resistors, and flips it by 180°.

Schematic of the Inverting Op-Amp Amplifier circuit

Simulation result

The simulator computed these waveforms from the circuit above, over the first 2 ms.

CH1 200 mV/divInput signalCH2 1 V/divOp-amp output200 µs/div

Numbers from the simulation

Computed by the simulator from the part values in the schematic.

Gain magnitude (peak to peak)
4.69 ×
Output peak voltage
2.35 V

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Open in the simulator

How it works

The op-amp holds its two inputs at almost the same voltage. The non-inverting input is grounded, so the inverting input also sits near 0 V. This point is called a virtual ground.

The current coming in through Rin equals the current leaving through Rf, so Vout = −Vin × Rf / Rin. With 47 kΩ and 10 kΩ, the gain is −4.7.

The output cannot go past the supply. On ±12 V the LM741 output clips about 1.5 V short of each rail.

Try changing

  1. Raise the generator amplitude to 3 V. The output should reach 14.1 V peak, past the supply limit, so the peaks clip.
  2. Change Rf to 100 kΩ for a gain of 10.
  3. Raise the frequency to 100 kHz. The LM741 cannot keep up: the gain falls and the output changes shape.

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